1. Field of the Invention
Embodiments of the present invention relate to a device for removing at least fluids from a mixture of particulate materials, comprising a container having a circular process chamber with a cylindrical external contour, an input device for inputting a mixture of particulate materials into the process chamber, a discharge device for discharging the particulate materials at least partly freed at least of the fluids from the process chamber, a feed device for feeding a fluidizing agent from below into the process chamber and at least one conditioning device for conditioning, in particular heating, the fluidizing agent in the direction of flow prior to the feed device, wherein up to n walls and n cells extending in the vertical direction are provided in the process chamber, where nεN, a first cell is in operative connection with the input device, an nth cell is in operative connection with the discharge device, the upper ends of the n cells are open, the first (n−1) cells are adapted to allow the fluidizing agent to flow therethrough from below through a base provided with first openings, and the walls between the n cells, from the first to the nth cell, each comprise at least one second opening for passage of particulate materials, as well as a method for removing at least fluids from a mixture of particulate materials in such a device.
2. Description of the Related Art
A device for removing fluids and/or solids is described, for example, in EP 07002861.8-1266, not pre-published, and will be explained in more detail below with reference to FIGS. 6 and 7.
FIG. 6 shows a drying device 1 having a container 2, comprising a substantially cylindrical outer skin 3. Therein, the container 2 is placed on a rack 4 to not only make the container 1 accessible for maintenance also from below, but also to facilitate an evacuation of dried particulate materials into a further processing plant. It can be seen in FIG. 6 that the external contour of the container 2 is substantially cylindrical. The geometrical structure of the container 2 and the components disposed therein is described below.
The container 2 set up on the rack 4 comprises at its lower end facing the rack 4, a vaulted base 5 in which there is disposed a not illustrated fan impeller by which a fluidizing agent in particular, overheated vapor, is circulated in the container 2. Within the container 2, there is disposed a substantially cylindrical super heater 6, so that the fluidizing agent is introduced from below into a substantially circular process chamber 20, which is designed between the super heater 6 and the outer skin 3 and into which materials to be treated can be input by way of a not illustrated input device. Therein, the process chamber 20 is delimited at its lower end by a distribution plate 7 held by means of a distribution plate holder which allows the passage of the fluidizing agent through a plurality of not shown openings from below, but does not permit the materials to be treated to fall through.
Above the distribution plate 7, there are disposed vertically aligned walls 8, which extend from the external wall of the super heater 6 to the container wall, i.e. the outer skin, and form n cells between them. The walls 8 can reach down to the distribution plate 7 or form a free space in between. The cells formed by the walls 8 are open at the top, so that the fluidizing agent flows through the cells from the bottom up and fluidizes the materials or particles to be treated, partly carrying them along upwards and transporting them into a downstream cell, if necessary. The fluidizing agent does not substantially flow through the nth cell or discharge cell provided with a not illustrated discharge device, so that any material entering such cell without a distribution plate from the top or along the distribution plate 7, reaches the base area and can be removed from the discharge cell by way of the discharge device, for example, a conveying screw.
Above the walls 8, there follow swirl blades 9 which can also be disposed, staggered, between the walls 8 in the circumferential direction and which correspond, in their vertical extension, approximately to the vertical extension of the walls 8 or extend beyond them, i.e. can be longer than the walls. The swirl blades 9, each one at its lower side facing the walls 8, are substantially aligned parallel to the walls 8, so that the pressure side of the swirl blades 9 is oriented at an angle of 0° to the axial component of the flow velocity of the fluidizing agent. The swirl blades 9 are designed curved in the embodiment illustrated in FIG. 6 and are oriented in such a way that the curve points from the input cell are in operative connection with the input device to the discharge cell, i.e. in the direction of flow of the particulate materials. If, for example, the input cell and the discharge cell are disposed next to each other interposing a wall 8, then the curve of the swirl blades 9 assigned to the input cell points away from the discharge cell, so that the particle and material stream has to be transported over the entire perimeter of the container 2 and thus of the process chamber 20 in order to reach the discharge cell.
At their upper end, the swirl blades 9 comprise a curve of up to 35° to the axial component of the flow velocity of the fluidizing agent to divert the stream of the fluidizing agent as well as that of the materials in the circumferential direction. The swirl blades 9 constitute an extension of the walls 8, wherein such extension can be designed with or without a gap between the swirl blades 9 and the walls 8. The swirl blades 9 can form a simple or double-curved area, i.e. comprise a curve around both the axial component and a radial component in order to divert the flow of the fluidizing agent and the direction of motion of the material or the solids according to the requirements. Instead of a curve, an inclination of otherwise straight-walled swirl blades 9 can also be provided for diverting the direction of flow.
Above the swirl blades 9, there is designed a transition area 10 embodied as a free space, which is provided without internals influencing the flow, so that the flow of the fluidizing agent as well as the transport of the same, together with the particles carried along in the fluidizing agent stream, can substantially take place unhindered. Such free space 10, the so-called transition area, is designed in an annular form and allows an uninterrupted, free, circular passage of both the materials and the fluidizing agent in the horizontal plane.
Above the swirl blades 9 and the transition area 10, there are disposed additional swirl blades 11, which also comprise a simple or double-curved area on their pressure side, with an entry angle of up to 15° in relation to the axial flow velocity component. In the same nomenclature, the exit angle is up to 90°, wherein the inside diameter of the blading corresponds to the outside diameter of the super heater 6.
The additional swirl blades 11 are a component of a dust separator 12, the outside diameter of which is smaller than the outside diameter of the process chamber 20 and thus smaller than the outside diameter of the container housing in the area of the walls 8 and the swirl blades 9. The outside diameter of the additional swirl blading corresponds to the outside diameter of the dust separator 12. By adapting the additional swirl blading to the swirl blades 9, the construction of the device 1 will be optimized with regard to the pressure loss, so that the overall device can be operated at a high level of efficiency. Therein, the external contour 3 of the container 2 is cylindrical at least up to the level of the swirl blades, in the present case up to the level of the dust separator 12 or the additional swirl blades 11, which avoids a material-intensive design of the container 2, preferably designed as a pressure container. The swirl blading generates and supports a pre-swirl or the swirl flow above a fluidized bed present in the chamber 20, which ensures that the required and desired further transport from the input cell to the discharge cell is not only supported for fine particles. Within the dust separator 12, there is generated a centrifugal field in which the dust particles and particulate materials carried along are moved around externally and are discharged through an opening.
Above the additional swirl blades 11, there are disposed return blades 13, oriented opposite the swirl direction, which redirect the swirl of the fluidizing agent, transforming it into a static pressure to feed the fluidizing agent into the super heater 6. The return or back-swirl blades 13 also comprise a simple or double-curved or inclined area with an entry angle of up to 90° in relation to the axial flow velocity component of the fluidizing agents, wherein the exit angle is up to 10° in the same nomenclature. The inside diameter of the blading corresponds to the outside diameter of an outlet pipe 14, while the outside diameter of the blading corresponds to the inside diameter of the super heater 6. By way of the upper opening 14a as shown in FIG. 6, vapor can escape from the container 2 and can be reused, preferably energetically, in another process.
FIG. 7 illustrates a horizontal section along the line D-D of FIG. 6. At the lower end of FIG. 7, there is shown the input cell 15, which is in operative connection with the not illustrated input device, for example, a conveying screw, and which is disposed directly next to the discharge cell 17, wherein the input cell 15 and the discharge cell 17 are fluidically separated from each other in such way that a direct transition of the material from the input cell 15 to the discharge cell 17 is prevented. Starting from the input cell 15, it follows a plurality of processing cells 16 that are separated from each other by the intermediate walls 8. Therein, the intermediate walls 8 can border directly on the container wall or can be suspended at a certain distance thereof within the annular process chamber 20 which is delimited by the distribution plate 7 at its lower side and by the lower side of the swirl blades 9 at its upper side. Within the processing cells 16, intermediate heating walls 18 can be disposed to provide additional thermal energy for the drying process.
Furthermore, EP 0 955 511 B1 describes an alternative device for drying granular material by means of overheated vapor in which an arrangement for automatically regulating a particle flow from cell to cell, preferably comprising a shutter for an opening of a wall between two adjacent cells, is provided between all processing cells, including an input cell and a discharge cell. However, the use of such shutters involves the risk that an accumulation of granular material occurs before each closed shutter, so that the respective shutter gets jammed and can thus no longer be opened purposefully, with the consequence that neither the degree of drying nor the discharge quantity of dried granular material can be adjusted reproducibly.